Portable Recorder Noise:The Sounds of Silence

You may have wondered why our new speech samples have gaps of silence in them. We made them that way intentionally, in response to several customer requests for quieter -- even silent -- sound samples in order to assess the relative noise floor of each recorder.

By "noise floor," I mean the background noise generated by the unit itself when it makes a recording. As you might have guessed, quieter is better when it comes to portable recorder noise.

Compared to what was available only a few years ago, today's portable audio recorders are very quiet. Not perfectly pristine, mind you, but very quiet. Even the most economical recorder we sell, the Zoom H2, sounds noticeably better than a mini disc recorder and much better than any cassette deck.

For casual live recording, portable recorder noise may not be a big concern, especially if you record relatively loud sounds or have a knack for setting your levels well (as high as possible without clipping or distortion).

On the other hand, if you record relatively quiet sounds (acoustic, natural and/or ambient), portable recorder noise can be your nemesis, especially if you want to layer or otherwise process your sound files after recording.

We think that most of the portable audio recorders available today already sound good enough for most recording situations, without the need for external mics or preamps. For circumstances like jam sessions, lessons or rehearsals, use your trusty handheld recorder on its own. You'll get perfectly good if not excellent results most of the time. When you want cleaner, more professional-sounding results, try these tips:

Upgrade to the best unit you can afford. A higher price usually means better build quality and electronics, which in turn usually means less portable recorder noise.

Use an external mic. For better results, plug your best condenser microphones into a field recorder with balanced, XLR MIC inputs and phantom power. If your recorder doesn't have XLR inputs or phantom power, use a phantom power supply.

Use an external mic and an external mic preamp. For the best results, connect your external mic to an external mic preamp and then connect the preamp to the LINE IN port of your recorder. (The MIC IN port on your recorder has a small amplifier in it to boost the mic signal. The LINE IN port doesn't have an amplifier, so you need to bring the signal to line level before you plug anything into the LINE IN port).

Having trouble with the samples? Try using Internet Explorer 9 or Safari. If you don't see anything in IE9, click on the yellow bar at the top of the browser screen, select "Allow Blocked Content" and then "Yes."

Still having trouble? Try closing any other open windows, clearing your browser's cache, updating your flash plug-in and allowing javascript.

To show what we mean by portable recorder noise, we've made the samples below with our most popular recorders. We've tested internal and external mics, dynamic and condenser external mics and mic and line inputs. What differences do you hear?

Details: For the condenser mic samples, we used a Rode NT1-A. For the dynamic mic samples, we used a Heil PR-35. This is consistent with our belief that you'll have to spend at least $200 or so to improve upon the sound quality you can achieve with the internal mics in your handheld recorder. Your mileage may vary.

To save time, we used a Samson S-Split 3-way mic splitter to make 3 mic samples at a time. We used an Allen & Heath MixWizard WZ3 16:2 mixer to make 6 line input samples at a time.

The original samples were 24-bit/44.1kHz wav files. For optimal web listening, the samples were then converted to 192kbps/16-bit/44.1kHz mp3 files with dBpowerAmp Music Converter.

What do you mean by "unbalanced"?

By "unbalanced," I mean "not grounded." A balanced connection uses 3 wires. Two separate signal wires inside a shield carry + and - signals (opposite polarity). The shield is connected to ground. It encases the signal wires and protects them from outside interference.

A balanced connection is less susceptible to noise from things like electric motors, computer hash and radio frequencies because those interferences hit the shield and are directed to ground.

An unbalanced connection uses 2 wires. One of the signal wires is the shield, the other is the + signal. Any noise picked up on the shield is fed directly into the mic amplifier.

What's plug-in power?

Plug-in-power is a small voltage (3-5V) required by certain consumer-level electret microphones (like the Edirol CS-15 or one of the small Sony Stereo mics -- they can be pretty good) and delivered by many portable audio recorders.

It's similar to phantom power, but not interchangeable with it. You can't power a standard, pro-level condenser mic with plug-in-power, nor can you run a plug-in-power mic from standard phantom power.

What's phantom power?

Phantom power is a DC voltage that is fed back through a microphone cable from a mic preamplifier or mixer to a condenser microphone in order to run its internal electronics. The term "phantom power" was coined because no additional wires or connections are used to distribute the DC power. Most condenser mics have 3-pin balanced (XLR or 1/4" TRS) connectors and require 48V phantom power.

Most mixers and external mic preamps have a built-in, 48-volt phantom power supply that can be sent to the condenser mic through the mic cable.

What's a mic pre-amp?

A mic preamp is a device that supplies preamplification to a microphone. Preamplification is not the same as phantom power. All microphones require preamplification to raise signal levels by approximately 60dB, but only condenser microphones require phantom power in addition to preamplification.

"Good" mic pre-amps are those that deliver sufficient microphone preamplification without adding a lot of noise to the mic signal. In our experience, most handheld recorders have decent preamps for their internal mics, but relatively weak preamps for their external mic jacks.